The present invention refers to a method for the production of plastic molded skins having different subregions, as well as a device for the production of such plastic molded skins. The afore-stated plastic molded skins are provided especially for use in interior paneling and instrument dashboards of motor vehicles and include subregions having varying properties, in particular, also providing the subregions with different colors.
Methods for the production of multicolored plastic molded skins are known since some time now. Thus, for example EP 0 972 625 A1 describes a device for rotation sintering of plastic molded skins for the production of instrument dashboards or interior paneling of motor vehicles and are comprised essentially of a heatable mold tool as well as two differently equipped container fitting with the mold tool and containing plastic powder, wherein the containers are utilized sequentially in two different work steps each in combination with the mold tool. The first plastic powder container includes a bowl-shaped projection which extends into the interior of the mold tool covering a portion of the surface of the mold tool. This powder container is utilized with a first plastic powder in a first work step, wherein the first powder is melted at the exposed surface of the warmed mold tool, while the area underneath the bowl-shaped cover of the mold tool remains free of powder.
In the second work step a second powder box is utilized, which contains a differently colored powder and does not include a suitable projection for a cover, such that during the repeated rotation sintering, the second powder melts at the area of the surface of the mold tool previously maintained exposed and there, forms a molded skin in a different color, which combines with the molded skin of the first molded skin to form a multicolored molded skin.
The problem with the device is the high operative expenditure, in particular also for the sealing of the cover (mask), where, especially in complicated molds, there is the danger of leakage and where blurring of the color borders can take place.
In DE 10 2005 020 492 A1 and in DE 10 2005 020 493 A1 a device or a method for the production of multicolored plastic molded skins are described, in particular for motor vehicle parts, such as for example instrument dash boards or door paneling, wherein the plastic molded skins are built by the sintering method through means of sequential multiple continuous melting of plastic powders of different colors at the surface of a heated mold tool. The areas to be provided with plastic powders of different colors at a surface of the mold tool are separated from each other by projections or webs. The covering or mask which in this case is also integrated into the powder container is, at its edges, provided with a gasket that is supported by the webs. In addition, an above atmospheric pressure is produced in the covered surface areas bordered by the webs. In this manner, the problem of the exact color separation is solved, however, in this case also, there is a relatively high expenditure in apparatus required, in particular, in order to integrate the mask as well as the required energy supply for the locking and sealing of the mask at the mold tool surface, as well as the production of the above atmospheric pressure in the masked area integrated in a corresponding powder box.
As an additional problem there is the fact that such masked powder containers, or those provided with covers or similar mold tool counter parts are provided with a series of additional cables and tubes in order to realize the functional capability of the mask. These cable and tubes packets render the manufacturing process undesirably complex and thereby causing considerable spatial restrictions.
Thus, the problem remained to realize a masking technique for the production of plastic molded skins with subregions of different properties, in particular, areas having different coloring, that do not exhibit the drawbacks of the prior art.